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Revision 1.28 by root, Tue Nov 27 20:26:50 2007 UTC vs.
Revision 1.49 by root, Wed Dec 12 04:53:58 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-12-12" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
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196\& return 0; 196\& return 0;
197\& } 197\& }
198.Ve 198.Ve
199.SH "DESCRIPTION" 199.SH "DESCRIPTION"
200.IX Header "DESCRIPTION" 200.IX Header "DESCRIPTION"
201The newest version of this document is also available as a html-formatted
202web page you might find easier to navigate when reading it for the first
203time: <http://cvs.schmorp.de/libev/ev.html>.
204.PP
201Libev is an event loop: you register interest in certain events (such as a 205Libev is an event loop: you register interest in certain events (such as a
202file descriptor being readable or a timeout occuring), and it will manage 206file descriptor being readable or a timeout occuring), and it will manage
203these event sources and provide your program with events. 207these event sources and provide your program with events.
204.PP 208.PP
205To do this, it must take more or less complete control over your process 209To do this, it must take more or less complete control over your process
… …
210watchers\fR, which are relatively small C structures you initialise with the 214watchers\fR, which are relatively small C structures you initialise with the
211details of the event, and then hand it over to libev by \fIstarting\fR the 215details of the event, and then hand it over to libev by \fIstarting\fR the
212watcher. 216watcher.
213.SH "FEATURES" 217.SH "FEATURES"
214.IX Header "FEATURES" 218.IX Header "FEATURES"
215Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the linux-specific \f(CW\*(C`epoll\*(C'\fR, the 219Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the
216bsd-specific \f(CW\*(C`kqueue\*(C'\fR and the solaris-specific event port mechanisms 220BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms
217for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), 221for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface
222(for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers
218absolute timers with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous 223with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals
219signals (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and 224(\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event
220event watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, 225watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
221\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as 226\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as
222file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events 227file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
223(\f(CW\*(C`ev_fork\*(C'\fR). 228(\f(CW\*(C`ev_fork\*(C'\fR).
224.PP 229.PP
225It also is quite fast (see this 230It also is quite fast (see this
… …
254.IX Item "int ev_version_major ()" 259.IX Item "int ev_version_major ()"
255.PD 0 260.PD 0
256.IP "int ev_version_minor ()" 4 261.IP "int ev_version_minor ()" 4
257.IX Item "int ev_version_minor ()" 262.IX Item "int ev_version_minor ()"
258.PD 263.PD
259You can find out the major and minor version numbers of the library 264You can find out the major and minor \s-1ABI\s0 version numbers of the library
260you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and 265you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and
261\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global 266\&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global
262symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the 267symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the
263version of the library your program was compiled against. 268version of the library your program was compiled against.
264.Sp 269.Sp
270These version numbers refer to the \s-1ABI\s0 version of the library, not the
271release version.
272.Sp
265Usually, it's a good idea to terminate if the major versions mismatch, 273Usually, it's a good idea to terminate if the major versions mismatch,
266as this indicates an incompatible change. Minor versions are usually 274as this indicates an incompatible change. Minor versions are usually
267compatible to older versions, so a larger minor version alone is usually 275compatible to older versions, so a larger minor version alone is usually
268not a problem. 276not a problem.
269.Sp 277.Sp
270Example: Make sure we haven't accidentally been linked against the wrong 278Example: Make sure we haven't accidentally been linked against the wrong
271version. 279version.
… …
304might be supported on the current system, you would need to look at 312might be supported on the current system, you would need to look at
305\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for 313\&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for
306recommended ones. 314recommended ones.
307.Sp 315.Sp
308See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. 316See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
309.IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4 317.IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4
310.IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 318.IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))"
311Sets the allocation function to use (the prototype and semantics are 319Sets the allocation function to use (the prototype is similar \- the
312identical to the realloc C function). It is used to allocate and free 320semantics is identical \- to the realloc C function). It is used to
313memory (no surprises here). If it returns zero when memory needs to be 321allocate and free memory (no surprises here). If it returns zero when
314allocated, the library might abort or take some potentially destructive 322memory needs to be allocated, the library might abort or take some
315action. The default is your system realloc function. 323potentially destructive action. The default is your system realloc
324function.
316.Sp 325.Sp
317You could override this function in high-availability programs to, say, 326You could override this function in high-availability programs to, say,
318free some memory if it cannot allocate memory, to use a special allocator, 327free some memory if it cannot allocate memory, to use a special allocator,
319or even to sleep a while and retry until some memory is available. 328or even to sleep a while and retry until some memory is available.
320.Sp 329.Sp
… …
409or setgid) then libev will \fInot\fR look at the environment variable 418or setgid) then libev will \fInot\fR look at the environment variable
410\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will 419\&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will
411override the flags completely if it is found in the environment. This is 420override the flags completely if it is found in the environment. This is
412useful to try out specific backends to test their performance, or to work 421useful to try out specific backends to test their performance, or to work
413around bugs. 422around bugs.
423.ie n .IP """EVFLAG_FORKCHECK""" 4
424.el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4
425.IX Item "EVFLAG_FORKCHECK"
426Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after
427a fork, you can also make libev check for a fork in each iteration by
428enabling this flag.
429.Sp
430This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop,
431and thus this might slow down your event loop if you do a lot of loop
432iterations and little real work, but is usually not noticeable (on my
433Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence
434without a syscall and thus \fIvery\fR fast, but my Linux system also has
435\&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster).
436.Sp
437The big advantage of this flag is that you can forget about fork (and
438forget about forgetting to tell libev about forking) when you use this
439flag.
440.Sp
441This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR
442environment variable.
414.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 443.ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4
415.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 444.el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4
416.IX Item "EVBACKEND_SELECT (value 1, portable select backend)" 445.IX Item "EVBACKEND_SELECT (value 1, portable select backend)"
417This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as 446This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as
418libev tries to roll its own fd_set with no limits on the number of fds, 447libev tries to roll its own fd_set with no limits on the number of fds,
… …
559.IP "ev_loop_fork (loop)" 4 588.IP "ev_loop_fork (loop)" 4
560.IX Item "ev_loop_fork (loop)" 589.IX Item "ev_loop_fork (loop)"
561Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by 590Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by
562\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop 591\&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop
563after fork, and how you do this is entirely your own problem. 592after fork, and how you do this is entirely your own problem.
593.IP "unsigned int ev_loop_count (loop)" 4
594.IX Item "unsigned int ev_loop_count (loop)"
595Returns the count of loop iterations for the loop, which is identical to
596the number of times libev did poll for new events. It starts at \f(CW0\fR and
597happily wraps around with enough iterations.
598.Sp
599This value can sometimes be useful as a generation counter of sorts (it
600\&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with
601\&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls.
564.IP "unsigned int ev_backend (loop)" 4 602.IP "unsigned int ev_backend (loop)" 4
565.IX Item "unsigned int ev_backend (loop)" 603.IX Item "unsigned int ev_backend (loop)"
566Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in 604Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in
567use. 605use.
568.IP "ev_tstamp ev_now (loop)" 4 606.IP "ev_tstamp ev_now (loop)" 4
… …
599libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is 637libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is
600usually a better approach for this kind of thing. 638usually a better approach for this kind of thing.
601.Sp 639.Sp
602Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: 640Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does:
603.Sp 641.Sp
604.Vb 18 642.Vb 19
643\& - Before the first iteration, call any pending watchers.
605\& * If there are no active watchers (reference count is zero), return. 644\& * If there are no active watchers (reference count is zero), return.
606\& - Queue prepare watchers and then call all outstanding watchers. 645\& - Queue all prepare watchers and then call all outstanding watchers.
607\& - If we have been forked, recreate the kernel state. 646\& - If we have been forked, recreate the kernel state.
608\& - Update the kernel state with all outstanding changes. 647\& - Update the kernel state with all outstanding changes.
609\& - Update the "event loop time". 648\& - Update the "event loop time".
610\& - Calculate for how long to block. 649\& - Calculate for how long to block.
611\& - Block the process, waiting for any events. 650\& - Block the process, waiting for any events.
… …
854.IP "bool ev_is_pending (ev_TYPE *watcher)" 4 893.IP "bool ev_is_pending (ev_TYPE *watcher)" 4
855.IX Item "bool ev_is_pending (ev_TYPE *watcher)" 894.IX Item "bool ev_is_pending (ev_TYPE *watcher)"
856Returns a true value iff the watcher is pending, (i.e. it has outstanding 895Returns a true value iff the watcher is pending, (i.e. it has outstanding
857events but its callback has not yet been invoked). As long as a watcher 896events but its callback has not yet been invoked). As long as a watcher
858is pending (but not active) you must not call an init function on it (but 897is pending (but not active) you must not call an init function on it (but
859\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 898\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must
860libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 899make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR
900it).
861.IP "callback = ev_cb (ev_TYPE *watcher)" 4 901.IP "callback ev_cb (ev_TYPE *watcher)" 4
862.IX Item "callback = ev_cb (ev_TYPE *watcher)" 902.IX Item "callback ev_cb (ev_TYPE *watcher)"
863Returns the callback currently set on the watcher. 903Returns the callback currently set on the watcher.
864.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 904.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
865.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 905.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
866Change the callback. You can change the callback at virtually any time 906Change the callback. You can change the callback at virtually any time
867(modulo threads). 907(modulo threads).
908.IP "ev_set_priority (ev_TYPE *watcher, priority)" 4
909.IX Item "ev_set_priority (ev_TYPE *watcher, priority)"
910.PD 0
911.IP "int ev_priority (ev_TYPE *watcher)" 4
912.IX Item "int ev_priority (ev_TYPE *watcher)"
913.PD
914Set and query the priority of the watcher. The priority is a small
915integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR
916(default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked
917before watchers with lower priority, but priority will not keep watchers
918from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers).
919.Sp
920This means that priorities are \fIonly\fR used for ordering callback
921invocation after new events have been received. This is useful, for
922example, to reduce latency after idling, or more often, to bind two
923watchers on the same event and make sure one is called first.
924.Sp
925If you need to suppress invocation when higher priority events are pending
926you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality.
927.Sp
928You \fImust not\fR change the priority of a watcher as long as it is active or
929pending.
930.Sp
931The default priority used by watchers when no priority has been set is
932always \f(CW0\fR, which is supposed to not be too high and not be too low :).
933.Sp
934Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is
935fine, as long as you do not mind that the priority value you query might
936or might not have been adjusted to be within valid range.
937.IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4
938.IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)"
939Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither
940\&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback
941can deal with that fact.
942.IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4
943.IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)"
944If the watcher is pending, this function returns clears its pending status
945and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the
946watcher isn't pending it does nothing and returns \f(CW0\fR.
868.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" 947.Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0"
869.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" 948.IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER"
870Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change 949Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change
871and read at any time, libev will completely ignore it. This can be used 950and read at any time, libev will completely ignore it. This can be used
872to associate arbitrary data with your watcher. If you need more data and 951to associate arbitrary data with your watcher. If you need more data and
… …
893\& struct my_io *w = (struct my_io *)w_; 972\& struct my_io *w = (struct my_io *)w_;
894\& ... 973\& ...
895\& } 974\& }
896.Ve 975.Ve
897.PP 976.PP
898More interesting and less C\-conformant ways of catsing your callback type 977More interesting and less C\-conformant ways of casting your callback type
899have been omitted.... 978instead have been omitted.
979.PP
980Another common scenario is having some data structure with multiple
981watchers:
982.PP
983.Vb 6
984\& struct my_biggy
985\& {
986\& int some_data;
987\& ev_timer t1;
988\& ev_timer t2;
989\& }
990.Ve
991.PP
992In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
993you need to use \f(CW\*(C`offsetof\*(C'\fR:
994.PP
995.Vb 1
996\& #include <stddef.h>
997.Ve
998.PP
999.Vb 6
1000\& static void
1001\& t1_cb (EV_P_ struct ev_timer *w, int revents)
1002\& {
1003\& struct my_biggy big = (struct my_biggy *
1004\& (((char *)w) - offsetof (struct my_biggy, t1));
1005\& }
1006.Ve
1007.PP
1008.Vb 6
1009\& static void
1010\& t2_cb (EV_P_ struct ev_timer *w, int revents)
1011\& {
1012\& struct my_biggy big = (struct my_biggy *
1013\& (((char *)w) - offsetof (struct my_biggy, t2));
1014\& }
1015.Ve
900.SH "WATCHER TYPES" 1016.SH "WATCHER TYPES"
901.IX Header "WATCHER TYPES" 1017.IX Header "WATCHER TYPES"
902This section describes each watcher in detail, but will not repeat 1018This section describes each watcher in detail, but will not repeat
903information given in the last section. Any initialisation/set macros, 1019information given in the last section. Any initialisation/set macros,
904functions and members specific to the watcher type are explained. 1020functions and members specific to the watcher type are explained.
… …
946it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning 1062it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning
947\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. 1063\&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives.
948.PP 1064.PP
949If you cannot run the fd in non-blocking mode (for example you should not 1065If you cannot run the fd in non-blocking mode (for example you should not
950play around with an Xlib connection), then you have to seperately re-test 1066play around with an Xlib connection), then you have to seperately re-test
951wether a file descriptor is really ready with a known-to-be good interface 1067whether a file descriptor is really ready with a known-to-be good interface
952such as poll (fortunately in our Xlib example, Xlib already does this on 1068such as poll (fortunately in our Xlib example, Xlib already does this on
953its own, so its quite safe to use). 1069its own, so its quite safe to use).
1070.PP
1071\fIThe special problem of disappearing file descriptors\fR
1072.IX Subsection "The special problem of disappearing file descriptors"
1073.PP
1074Some backends (e.g kqueue, epoll) need to be told about closing a file
1075descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means,
1076such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file
1077descriptor, but when it goes away, the operating system will silently drop
1078this interest. If another file descriptor with the same number then is
1079registered with libev, there is no efficient way to see that this is, in
1080fact, a different file descriptor.
1081.PP
1082To avoid having to explicitly tell libev about such cases, libev follows
1083the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
1084will assume that this is potentially a new file descriptor, otherwise
1085it is assumed that the file descriptor stays the same. That means that
1086you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the
1087descriptor even if the file descriptor number itself did not change.
1088.PP
1089This is how one would do it normally anyway, the important point is that
1090the libev application should not optimise around libev but should leave
1091optimisations to libev.
954.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1092.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
955.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1093.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
956.PD 0 1094.PD 0
957.IP "ev_io_set (ev_io *, int fd, int events)" 4 1095.IP "ev_io_set (ev_io *, int fd, int events)" 4
958.IX Item "ev_io_set (ev_io *, int fd, int events)" 1096.IX Item "ev_io_set (ev_io *, int fd, int events)"
… …
1032.IP "ev_timer_again (loop)" 4 1170.IP "ev_timer_again (loop)" 4
1033.IX Item "ev_timer_again (loop)" 1171.IX Item "ev_timer_again (loop)"
1034This will act as if the timer timed out and restart it again if it is 1172This will act as if the timer timed out and restart it again if it is
1035repeating. The exact semantics are: 1173repeating. The exact semantics are:
1036.Sp 1174.Sp
1175If the timer is pending, its pending status is cleared.
1176.Sp
1037If the timer is started but nonrepeating, stop it. 1177If the timer is started but nonrepeating, stop it (as if it timed out).
1038.Sp 1178.Sp
1039If the timer is repeating, either start it if necessary (with the repeat 1179If the timer is repeating, either start it if necessary (with the
1040value), or reset the running timer to the repeat value. 1180\&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value.
1041.Sp 1181.Sp
1042This sounds a bit complicated, but here is a useful and typical 1182This sounds a bit complicated, but here is a useful and typical
1043example: Imagine you have a tcp connection and you want a so-called 1183example: Imagine you have a tcp connection and you want a so-called idle
1044idle timeout, that is, you want to be called when there have been, 1184timeout, that is, you want to be called when there have been, say, 60
1045say, 60 seconds of inactivity on the socket. The easiest way to do 1185seconds of inactivity on the socket. The easiest way to do this is to
1046this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling 1186configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call
1047\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If 1187\&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If
1048you go into an idle state where you do not expect data to travel on the 1188you go into an idle state where you do not expect data to travel on the
1049socket, you can stop the timer, and again will automatically restart it if 1189socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will
1050need be. 1190automatically restart it if need be.
1051.Sp 1191.Sp
1052You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether 1192That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR
1053and only ever use the \f(CW\*(C`repeat\*(C'\fR value: 1193altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR:
1054.Sp 1194.Sp
1055.Vb 8 1195.Vb 8
1056\& ev_timer_init (timer, callback, 0., 5.); 1196\& ev_timer_init (timer, callback, 0., 5.);
1057\& ev_timer_again (loop, timer); 1197\& ev_timer_again (loop, timer);
1058\& ... 1198\& ...
… …
1061\& ... 1201\& ...
1062\& timer->again = 10.; 1202\& timer->again = 10.;
1063\& ev_timer_again (loop, timer); 1203\& ev_timer_again (loop, timer);
1064.Ve 1204.Ve
1065.Sp 1205.Sp
1066This is more efficient then stopping/starting the timer eahc time you want 1206This is more slightly efficient then stopping/starting the timer each time
1067to modify its timeout value. 1207you want to modify its timeout value.
1068.IP "ev_tstamp repeat [read\-write]" 4 1208.IP "ev_tstamp repeat [read\-write]" 4
1069.IX Item "ev_tstamp repeat [read-write]" 1209.IX Item "ev_tstamp repeat [read-write]"
1070The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 1210The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1071or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), 1211or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1072which is also when any modifications are taken into account. 1212which is also when any modifications are taken into account.
… …
1120but on wallclock time (absolute time). You can tell a periodic watcher 1260but on wallclock time (absolute time). You can tell a periodic watcher
1121to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a 1261to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a
1122periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () 1262periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now ()
1123+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will 1263+ 10.\*(C'\fR) and then reset your system clock to the last year, then it will
1124take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger 1264take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger
1125roughly 10 seconds later and of course not if you reset your system time 1265roughly 10 seconds later).
1126again).
1127.PP 1266.PP
1128They can also be used to implement vastly more complex timers, such as 1267They can also be used to implement vastly more complex timers, such as
1129triggering an event on eahc midnight, local time. 1268triggering an event on each midnight, local time or other, complicated,
1269rules.
1130.PP 1270.PP
1131As with timers, the callback is guarenteed to be invoked only when the 1271As with timers, the callback is guarenteed to be invoked only when the
1132time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1272time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1133during the same loop iteration then order of execution is undefined. 1273during the same loop iteration then order of execution is undefined.
1134.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1274.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
… …
1138.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 1278.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
1139.PD 1279.PD
1140Lots of arguments, lets sort it out... There are basically three modes of 1280Lots of arguments, lets sort it out... There are basically three modes of
1141operation, and we will explain them from simplest to complex: 1281operation, and we will explain them from simplest to complex:
1142.RS 4 1282.RS 4
1143.IP "* absolute timer (interval = reschedule_cb = 0)" 4 1283.IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4
1144.IX Item "absolute timer (interval = reschedule_cb = 0)" 1284.IX Item "absolute timer (at = time, interval = reschedule_cb = 0)"
1145In this configuration the watcher triggers an event at the wallclock time 1285In this configuration the watcher triggers an event at the wallclock time
1146\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, 1286\&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs,
1147that is, if it is to be run at January 1st 2011 then it will run when the 1287that is, if it is to be run at January 1st 2011 then it will run when the
1148system time reaches or surpasses this time. 1288system time reaches or surpasses this time.
1149.IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 1289.IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4
1150.IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" 1290.IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)"
1151In this mode the watcher will always be scheduled to time out at the next 1291In this mode the watcher will always be scheduled to time out at the next
1152\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless 1292\&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative)
1153of any time jumps. 1293and then repeat, regardless of any time jumps.
1154.Sp 1294.Sp
1155This can be used to create timers that do not drift with respect to system 1295This can be used to create timers that do not drift with respect to system
1156time: 1296time:
1157.Sp 1297.Sp
1158.Vb 1 1298.Vb 1
… …
1165by 3600. 1305by 3600.
1166.Sp 1306.Sp
1167Another way to think about it (for the mathematically inclined) is that 1307Another way to think about it (for the mathematically inclined) is that
1168\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible 1308\&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible
1169time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. 1309time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps.
1310.Sp
1311For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near
1312\&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for
1313this value.
1170.IP "* manual reschedule mode (reschedule_cb = callback)" 4 1314.IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4
1171.IX Item "manual reschedule mode (reschedule_cb = callback)" 1315.IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)"
1172In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being 1316In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being
1173ignored. Instead, each time the periodic watcher gets scheduled, the 1317ignored. Instead, each time the periodic watcher gets scheduled, the
1174reschedule callback will be called with the watcher as first, and the 1318reschedule callback will be called with the watcher as first, and the
1175current time as second argument. 1319current time as second argument.
1176.Sp 1320.Sp
1177\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, 1321\&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher,
1178ever, or make any event loop modifications\fR. If you need to stop it, 1322ever, or make any event loop modifications\fR. If you need to stop it,
1179return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by 1323return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by
1180starting a prepare watcher). 1324starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is legal).
1181.Sp 1325.Sp
1182Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1326Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1183ev_tstamp now)\*(C'\fR, e.g.: 1327ev_tstamp now)\*(C'\fR, e.g.:
1184.Sp 1328.Sp
1185.Vb 4 1329.Vb 4
… …
1209.IX Item "ev_periodic_again (loop, ev_periodic *)" 1353.IX Item "ev_periodic_again (loop, ev_periodic *)"
1210Simply stops and restarts the periodic watcher again. This is only useful 1354Simply stops and restarts the periodic watcher again. This is only useful
1211when you changed some parameters or the reschedule callback would return 1355when you changed some parameters or the reschedule callback would return
1212a different time than the last time it was called (e.g. in a crond like 1356a different time than the last time it was called (e.g. in a crond like
1213program when the crontabs have changed). 1357program when the crontabs have changed).
1358.IP "ev_tstamp offset [read\-write]" 4
1359.IX Item "ev_tstamp offset [read-write]"
1360When repeating, this contains the offset value, otherwise this is the
1361absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR).
1362.Sp
1363Can be modified any time, but changes only take effect when the periodic
1364timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1214.IP "ev_tstamp interval [read\-write]" 4 1365.IP "ev_tstamp interval [read\-write]" 4
1215.IX Item "ev_tstamp interval [read-write]" 1366.IX Item "ev_tstamp interval [read-write]"
1216The current interval value. Can be modified any time, but changes only 1367The current interval value. Can be modified any time, but changes only
1217take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being 1368take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being
1218called. 1369called.
… …
1345not exist\*(R" is a status change like any other. The condition \*(L"path does 1496not exist\*(R" is a status change like any other. The condition \*(L"path does
1346not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is 1497not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1347otherwise always forced to be at least one) and all the other fields of 1498otherwise always forced to be at least one) and all the other fields of
1348the stat buffer having unspecified contents. 1499the stat buffer having unspecified contents.
1349.PP 1500.PP
1501The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is
1502relative and your working directory changes, the behaviour is undefined.
1503.PP
1350Since there is no standard to do this, the portable implementation simply 1504Since there is no standard to do this, the portable implementation simply
1351calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You 1505calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1352can specify a recommended polling interval for this case. If you specify 1506can specify a recommended polling interval for this case. If you specify
1353a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1507a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1354unspecified default\fR value will be used (which you can expect to be around 1508unspecified default\fR value will be used (which you can expect to be around
1355five seconds, although this might change dynamically). Libev will also 1509five seconds, although this might change dynamically). Libev will also
1356impose a minimum interval which is currently around \f(CW0.1\fR, but thats 1510impose a minimum interval which is currently around \f(CW0.1\fR, but thats
… …
1358.PP 1512.PP
1359This watcher type is not meant for massive numbers of stat watchers, 1513This watcher type is not meant for massive numbers of stat watchers,
1360as even with OS-supported change notifications, this can be 1514as even with OS-supported change notifications, this can be
1361resource\-intensive. 1515resource\-intensive.
1362.PP 1516.PP
1363At the time of this writing, no specific \s-1OS\s0 backends are implemented, but 1517At the time of this writing, only the Linux inotify interface is
1364if demand increases, at least a kqueue and inotify backend will be added. 1518implemented (implementing kqueue support is left as an exercise for the
1519reader). Inotify will be used to give hints only and should not change the
1520semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1521to fall back to regular polling again even with inotify, but changes are
1522usually detected immediately, and if the file exists there will be no
1523polling.
1365.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1524.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1366.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1525.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1367.PD 0 1526.PD 0
1368.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1527.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1369.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1528.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
1430\& ev_stat_start (loop, &passwd); 1589\& ev_stat_start (loop, &passwd);
1431.Ve 1590.Ve
1432.ie n .Sh """ev_idle"" \- when you've got nothing better to do..." 1591.ie n .Sh """ev_idle"" \- when you've got nothing better to do..."
1433.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." 1592.el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..."
1434.IX Subsection "ev_idle - when you've got nothing better to do..." 1593.IX Subsection "ev_idle - when you've got nothing better to do..."
1435Idle watchers trigger events when there are no other events are pending 1594Idle watchers trigger events when no other events of the same or higher
1436(prepare, check and other idle watchers do not count). That is, as long 1595priority are pending (prepare, check and other idle watchers do not
1437as your process is busy handling sockets or timeouts (or even signals, 1596count).
1438imagine) it will not be triggered. But when your process is idle all idle 1597.PP
1439watchers are being called again and again, once per event loop iteration \- 1598That is, as long as your process is busy handling sockets or timeouts
1599(or even signals, imagine) of the same or higher priority it will not be
1600triggered. But when your process is idle (or only lower-priority watchers
1601are pending), the idle watchers are being called once per event loop
1440until stopped, that is, or your process receives more events and becomes 1602iteration \- until stopped, that is, or your process receives more events
1441busy. 1603and becomes busy again with higher priority stuff.
1442.PP 1604.PP
1443The most noteworthy effect is that as long as any idle watchers are 1605The most noteworthy effect is that as long as any idle watchers are
1444active, the process will not block when waiting for new events. 1606active, the process will not block when waiting for new events.
1445.PP 1607.PP
1446Apart from keeping your process non-blocking (which is a useful 1608Apart from keeping your process non-blocking (which is a useful
… …
1509are ready to run (it's actually more complicated: it only runs coroutines 1671are ready to run (it's actually more complicated: it only runs coroutines
1510with priority higher than or equal to the event loop and one coroutine 1672with priority higher than or equal to the event loop and one coroutine
1511of lower priority, but only once, using idle watchers to keep the event 1673of lower priority, but only once, using idle watchers to keep the event
1512loop from blocking if lower-priority coroutines are active, thus mapping 1674loop from blocking if lower-priority coroutines are active, thus mapping
1513low-priority coroutines to idle/background tasks). 1675low-priority coroutines to idle/background tasks).
1676.PP
1677It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1678priority, to ensure that they are being run before any other watchers
1679after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1680too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1681supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
1682their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
1683loops those other event loops might be in an unusable state until their
1684\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
1685others).
1514.IP "ev_prepare_init (ev_prepare *, callback)" 4 1686.IP "ev_prepare_init (ev_prepare *, callback)" 4
1515.IX Item "ev_prepare_init (ev_prepare *, callback)" 1687.IX Item "ev_prepare_init (ev_prepare *, callback)"
1516.PD 0 1688.PD 0
1517.IP "ev_check_init (ev_check *, callback)" 4 1689.IP "ev_check_init (ev_check *, callback)" 4
1518.IX Item "ev_check_init (ev_check *, callback)" 1690.IX Item "ev_check_init (ev_check *, callback)"
1519.PD 1691.PD
1520Initialises and configures the prepare or check watcher \- they have no 1692Initialises and configures the prepare or check watcher \- they have no
1521parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR 1693parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR
1522macros, but using them is utterly, utterly and completely pointless. 1694macros, but using them is utterly, utterly and completely pointless.
1523.PP 1695.PP
1524Example: To include a library such as adns, you would add \s-1IO\s0 watchers 1696There are a number of principal ways to embed other event loops or modules
1525and a timeout watcher in a prepare handler, as required by libadns, and 1697into libev. Here are some ideas on how to include libadns into libev
1698(there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could
1699use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR
1700embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0
1701into the Glib event loop).
1702.PP
1703Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler,
1526in a check watcher, destroy them and call into libadns. What follows is 1704and in a check watcher, destroy them and call into libadns. What follows
1527pseudo-code only of course: 1705is pseudo-code only of course. This requires you to either use a low
1706priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as
1707the callbacks for the IO/timeout watchers might not have been called yet.
1528.PP 1708.PP
1529.Vb 2 1709.Vb 2
1530\& static ev_io iow [nfd]; 1710\& static ev_io iow [nfd];
1531\& static ev_timer tw; 1711\& static ev_timer tw;
1532.Ve 1712.Ve
1533.PP 1713.PP
1534.Vb 9 1714.Vb 4
1535\& static void 1715\& static void
1536\& io_cb (ev_loop *loop, ev_io *w, int revents) 1716\& io_cb (ev_loop *loop, ev_io *w, int revents)
1537\& { 1717\& {
1538\& // set the relevant poll flags
1539\& // could also call adns_processreadable etc. here
1540\& struct pollfd *fd = (struct pollfd *)w->data;
1541\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1542\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1543\& } 1718\& }
1544.Ve 1719.Ve
1545.PP 1720.PP
1546.Vb 7 1721.Vb 8
1547\& // create io watchers for each fd and a timer before blocking 1722\& // create io watchers for each fd and a timer before blocking
1548\& static void 1723\& static void
1549\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1724\& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1550\& { 1725\& {
1551\& int timeout = 3600000;truct pollfd fds [nfd]; 1726\& int timeout = 3600000;
1727\& struct pollfd fds [nfd];
1552\& // actual code will need to loop here and realloc etc. 1728\& // actual code will need to loop here and realloc etc.
1553\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); 1729\& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1554.Ve 1730.Ve
1555.PP 1731.PP
1556.Vb 3 1732.Vb 3
… …
1558\& ev_timer_init (&tw, 0, timeout * 1e-3); 1734\& ev_timer_init (&tw, 0, timeout * 1e-3);
1559\& ev_timer_start (loop, &tw); 1735\& ev_timer_start (loop, &tw);
1560.Ve 1736.Ve
1561.PP 1737.PP
1562.Vb 6 1738.Vb 6
1563\& // create on ev_io per pollfd 1739\& // create one ev_io per pollfd
1564\& for (int i = 0; i < nfd; ++i) 1740\& for (int i = 0; i < nfd; ++i)
1565\& { 1741\& {
1566\& ev_io_init (iow + i, io_cb, fds [i].fd, 1742\& ev_io_init (iow + i, io_cb, fds [i].fd,
1567\& ((fds [i].events & POLLIN ? EV_READ : 0) 1743\& ((fds [i].events & POLLIN ? EV_READ : 0)
1568\& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); 1744\& | (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1569.Ve 1745.Ve
1570.PP 1746.PP
1571.Vb 5 1747.Vb 4
1572\& fds [i].revents = 0; 1748\& fds [i].revents = 0;
1573\& iow [i].data = fds + i;
1574\& ev_io_start (loop, iow + i); 1749\& ev_io_start (loop, iow + i);
1575\& } 1750\& }
1576\& } 1751\& }
1577.Ve 1752.Ve
1578.PP 1753.PP
… …
1582\& adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1757\& adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1583\& { 1758\& {
1584\& ev_timer_stop (loop, &tw); 1759\& ev_timer_stop (loop, &tw);
1585.Ve 1760.Ve
1586.PP 1761.PP
1587.Vb 2 1762.Vb 8
1588\& for (int i = 0; i < nfd; ++i) 1763\& for (int i = 0; i < nfd; ++i)
1764\& {
1765\& // set the relevant poll flags
1766\& // could also call adns_processreadable etc. here
1767\& struct pollfd *fd = fds + i;
1768\& int revents = ev_clear_pending (iow + i);
1769\& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1770\& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1771.Ve
1772.PP
1773.Vb 3
1774\& // now stop the watcher
1589\& ev_io_stop (loop, iow + i); 1775\& ev_io_stop (loop, iow + i);
1776\& }
1590.Ve 1777.Ve
1591.PP 1778.PP
1592.Vb 2 1779.Vb 2
1593\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1780\& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1781\& }
1782.Ve
1783.PP
1784Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR
1785in the prepare watcher and would dispose of the check watcher.
1786.PP
1787Method 3: If the module to be embedded supports explicit event
1788notification (adns does), you can also make use of the actual watcher
1789callbacks, and only destroy/create the watchers in the prepare watcher.
1790.PP
1791.Vb 5
1792\& static void
1793\& timer_cb (EV_P_ ev_timer *w, int revents)
1794\& {
1795\& adns_state ads = (adns_state)w->data;
1796\& update_now (EV_A);
1797.Ve
1798.PP
1799.Vb 2
1800\& adns_processtimeouts (ads, &tv_now);
1801\& }
1802.Ve
1803.PP
1804.Vb 5
1805\& static void
1806\& io_cb (EV_P_ ev_io *w, int revents)
1807\& {
1808\& adns_state ads = (adns_state)w->data;
1809\& update_now (EV_A);
1810.Ve
1811.PP
1812.Vb 3
1813\& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1814\& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1815\& }
1816.Ve
1817.PP
1818.Vb 1
1819\& // do not ever call adns_afterpoll
1820.Ve
1821.PP
1822Method 4: Do not use a prepare or check watcher because the module you
1823want to embed is too inflexible to support it. Instead, youc na override
1824their poll function. The drawback with this solution is that the main
1825loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does
1826this.
1827.PP
1828.Vb 4
1829\& static gint
1830\& event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1831\& {
1832\& int got_events = 0;
1833.Ve
1834.PP
1835.Vb 2
1836\& for (n = 0; n < nfds; ++n)
1837\& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1838.Ve
1839.PP
1840.Vb 2
1841\& if (timeout >= 0)
1842\& // create/start timer
1843.Ve
1844.PP
1845.Vb 2
1846\& // poll
1847\& ev_loop (EV_A_ 0);
1848.Ve
1849.PP
1850.Vb 3
1851\& // stop timer again
1852\& if (timeout >= 0)
1853\& ev_timer_stop (EV_A_ &to);
1854.Ve
1855.PP
1856.Vb 3
1857\& // stop io watchers again - their callbacks should have set
1858\& for (n = 0; n < nfds; ++n)
1859\& ev_io_stop (EV_A_ iow [n]);
1860.Ve
1861.PP
1862.Vb 2
1863\& return got_events;
1594\& } 1864\& }
1595.Ve 1865.Ve
1596.ie n .Sh """ev_embed"" \- when one backend isn't enough..." 1866.ie n .Sh """ev_embed"" \- when one backend isn't enough..."
1597.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." 1867.el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..."
1598.IX Subsection "ev_embed - when one backend isn't enough..." 1868.IX Subsection "ev_embed - when one backend isn't enough..."
… …
1782.PP 2052.PP
1783.Vb 1 2053.Vb 1
1784\& #include <ev++.h> 2054\& #include <ev++.h>
1785.Ve 2055.Ve
1786.PP 2056.PP
1787(it is not installed by default). This automatically includes \fIev.h\fR 2057This automatically includes \fIev.h\fR and puts all of its definitions (many
1788and puts all of its definitions (many of them macros) into the global 2058of them macros) into the global namespace. All \*(C+ specific things are
1789namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. 2059put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding
2060options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR.
1790.PP 2061.PP
1791It should support all the same embedding options as \fIev.h\fR, most notably 2062Care has been taken to keep the overhead low. The only data member the \*(C+
1792\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. 2063classes add (compared to plain C\-style watchers) is the event loop pointer
2064that the watcher is associated with (or no additional members at all if
2065you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev).
2066.PP
2067Currently, functions, and static and non-static member functions can be
2068used as callbacks. Other types should be easy to add as long as they only
2069need one additional pointer for context. If you need support for other
2070types of functors please contact the author (preferably after implementing
2071it).
1793.PP 2072.PP
1794Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: 2073Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace:
1795.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 2074.ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4
1796.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 2075.el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4
1797.IX Item "ev::READ, ev::WRITE etc." 2076.IX Item "ev::READ, ev::WRITE etc."
… …
1809which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro 2088which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro
1810defines by many implementations. 2089defines by many implementations.
1811.Sp 2090.Sp
1812All of those classes have these methods: 2091All of those classes have these methods:
1813.RS 4 2092.RS 4
1814.IP "ev::TYPE::TYPE (object *, object::method *)" 4 2093.IP "ev::TYPE::TYPE ()" 4
1815.IX Item "ev::TYPE::TYPE (object *, object::method *)" 2094.IX Item "ev::TYPE::TYPE ()"
1816.PD 0 2095.PD 0
1817.IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 2096.IP "ev::TYPE::TYPE (struct ev_loop *)" 4
1818.IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 2097.IX Item "ev::TYPE::TYPE (struct ev_loop *)"
1819.IP "ev::TYPE::~TYPE" 4 2098.IP "ev::TYPE::~TYPE" 4
1820.IX Item "ev::TYPE::~TYPE" 2099.IX Item "ev::TYPE::~TYPE"
1821.PD 2100.PD
1822The constructor takes a pointer to an object and a method pointer to 2101The constructor (optionally) takes an event loop to associate the watcher
1823the event handler callback to call in this class. The constructor calls 2102with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR.
1824\&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method 2103.Sp
1825before starting it. If you do not specify a loop then the constructor 2104The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the
1826automatically associates the default loop with this watcher. 2105\&\f(CW\*(C`set\*(C'\fR method before starting it.
2106.Sp
2107It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR
2108method to set a callback before you can start the watcher.
2109.Sp
2110(The reason why you have to use a method is a limitation in \*(C+ which does
2111not allow explicit template arguments for constructors).
1827.Sp 2112.Sp
1828The destructor automatically stops the watcher if it is active. 2113The destructor automatically stops the watcher if it is active.
2114.IP "w\->set<class, &class::method> (object *)" 4
2115.IX Item "w->set<class, &class::method> (object *)"
2116This method sets the callback method to call. The method has to have a
2117signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as
2118first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as
2119parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher.
2120.Sp
2121This method synthesizes efficient thunking code to call your method from
2122the C callback that libev requires. If your compiler can inline your
2123callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and
2124your compiler is good :), then the method will be fully inlined into the
2125thunking function, making it as fast as a direct C callback.
2126.Sp
2127Example: simple class declaration and watcher initialisation
2128.Sp
2129.Vb 4
2130\& struct myclass
2131\& {
2132\& void io_cb (ev::io &w, int revents) { }
2133\& }
2134.Ve
2135.Sp
2136.Vb 3
2137\& myclass obj;
2138\& ev::io iow;
2139\& iow.set <myclass, &myclass::io_cb> (&obj);
2140.Ve
2141.IP "w\->set<function> (void *data = 0)" 4
2142.IX Item "w->set<function> (void *data = 0)"
2143Also sets a callback, but uses a static method or plain function as
2144callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's
2145\&\f(CW\*(C`data\*(C'\fR member and is free for you to use.
2146.Sp
2147The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR.
2148.Sp
2149See the method\-\f(CW\*(C`set\*(C'\fR above for more details.
2150.Sp
2151Example:
2152.Sp
2153.Vb 2
2154\& static void io_cb (ev::io &w, int revents) { }
2155\& iow.set <io_cb> ();
2156.Ve
1829.IP "w\->set (struct ev_loop *)" 4 2157.IP "w\->set (struct ev_loop *)" 4
1830.IX Item "w->set (struct ev_loop *)" 2158.IX Item "w->set (struct ev_loop *)"
1831Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only 2159Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only
1832do this when the watcher is inactive (and not pending either). 2160do this when the watcher is inactive (and not pending either).
1833.IP "w\->set ([args])" 4 2161.IP "w\->set ([args])" 4
1834.IX Item "w->set ([args])" 2162.IX Item "w->set ([args])"
1835Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be 2163Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be
1836called at least once. Unlike the C counterpart, an active watcher gets 2164called at least once. Unlike the C counterpart, an active watcher gets
1837automatically stopped and restarted. 2165automatically stopped and restarted when reconfiguring it with this
2166method.
1838.IP "w\->start ()" 4 2167.IP "w\->start ()" 4
1839.IX Item "w->start ()" 2168.IX Item "w->start ()"
1840Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the 2169Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
1841constructor already takes the loop. 2170constructor already stores the event loop.
1842.IP "w\->stop ()" 4 2171.IP "w\->stop ()" 4
1843.IX Item "w->stop ()" 2172.IX Item "w->stop ()"
1844Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2173Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
1845.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2174.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4
1846.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2175.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4
… …
1872.Vb 2 2201.Vb 2
1873\& myclass (); 2202\& myclass ();
1874\& } 2203\& }
1875.Ve 2204.Ve
1876.PP 2205.PP
1877.Vb 6 2206.Vb 4
1878\& myclass::myclass (int fd) 2207\& myclass::myclass (int fd)
1879\& : io (this, &myclass::io_cb),
1880\& idle (this, &myclass::idle_cb)
1881\& { 2208\& {
2209\& io .set <myclass, &myclass::io_cb > (this);
2210\& idle.set <myclass, &myclass::idle_cb> (this);
2211.Ve
2212.PP
2213.Vb 2
1882\& io.start (fd, ev::READ); 2214\& io.start (fd, ev::READ);
1883\& } 2215\& }
1884.Ve 2216.Ve
1885.SH "MACRO MAGIC" 2217.SH "MACRO MAGIC"
1886.IX Header "MACRO MAGIC" 2218.IX Header "MACRO MAGIC"
1887Libev can be compiled with a variety of options, the most fundemantal is 2219Libev can be compiled with a variety of options, the most fundemantal is
1888\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and 2220\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and
1889callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2221callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
1890.PP 2222.PP
1891To make it easier to write programs that cope with either variant, the 2223To make it easier to write programs that cope with either variant, the
1892following macros are defined: 2224following macros are defined:
1893.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2225.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
… …
1928.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 2260.el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4
1929.IX Item "EV_DEFAULT, EV_DEFAULT_" 2261.IX Item "EV_DEFAULT, EV_DEFAULT_"
1930Similar to the other two macros, this gives you the value of the default 2262Similar to the other two macros, this gives you the value of the default
1931loop, if multiple loops are supported (\*(L"ev loop default\*(R"). 2263loop, if multiple loops are supported (\*(L"ev loop default\*(R").
1932.PP 2264.PP
1933Example: Declare and initialise a check watcher, working regardless of 2265Example: Declare and initialise a check watcher, utilising the above
1934wether multiple loops are supported or not. 2266macros so it will work regardless of whether multiple loops are supported
2267or not.
1935.PP 2268.PP
1936.Vb 5 2269.Vb 5
1937\& static void 2270\& static void
1938\& check_cb (EV_P_ ev_timer *w, int revents) 2271\& check_cb (EV_P_ ev_timer *w, int revents)
1939\& { 2272\& {
… …
2002.Vb 1 2335.Vb 1
2003\& ev_win32.c required on win32 platforms only 2336\& ev_win32.c required on win32 platforms only
2004.Ve 2337.Ve
2005.PP 2338.PP
2006.Vb 5 2339.Vb 5
2007\& ev_select.c only when select backend is enabled (which is by default) 2340\& ev_select.c only when select backend is enabled (which is enabled by default)
2008\& ev_poll.c only when poll backend is enabled (disabled by default) 2341\& ev_poll.c only when poll backend is enabled (disabled by default)
2009\& ev_epoll.c only when the epoll backend is enabled (disabled by default) 2342\& ev_epoll.c only when the epoll backend is enabled (disabled by default)
2010\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2343\& ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2011\& ev_port.c only when the solaris port backend is enabled (disabled by default) 2344\& ev_port.c only when the solaris port backend is enabled (disabled by default)
2012.Ve 2345.Ve
… …
2133otherwise another method will be used as fallback. This is the preferred 2466otherwise another method will be used as fallback. This is the preferred
2134backend for Solaris 10 systems. 2467backend for Solaris 10 systems.
2135.IP "\s-1EV_USE_DEVPOLL\s0" 4 2468.IP "\s-1EV_USE_DEVPOLL\s0" 4
2136.IX Item "EV_USE_DEVPOLL" 2469.IX Item "EV_USE_DEVPOLL"
2137reserved for future expansion, works like the \s-1USE\s0 symbols above. 2470reserved for future expansion, works like the \s-1USE\s0 symbols above.
2471.IP "\s-1EV_USE_INOTIFY\s0" 4
2472.IX Item "EV_USE_INOTIFY"
2473If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2474interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2475be detected at runtime.
2138.IP "\s-1EV_H\s0" 4 2476.IP "\s-1EV_H\s0" 4
2139.IX Item "EV_H" 2477.IX Item "EV_H"
2140The name of the \fIev.h\fR header file used to include it. The default if 2478The name of the \fIev.h\fR header file used to include it. The default if
2141undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This 2479undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2142can be used to virtually rename the \fIev.h\fR header file in case of conflicts. 2480can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
… …
2160If undefined or defined to \f(CW1\fR, then all event-loop-specific functions 2498If undefined or defined to \f(CW1\fR, then all event-loop-specific functions
2161will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create 2499will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create
2162additional independent event loops. Otherwise there will be no support 2500additional independent event loops. Otherwise there will be no support
2163for multiple event loops and there is no first event loop pointer 2501for multiple event loops and there is no first event loop pointer
2164argument. Instead, all functions act on the single default loop. 2502argument. Instead, all functions act on the single default loop.
2503.IP "\s-1EV_MINPRI\s0" 4
2504.IX Item "EV_MINPRI"
2505.PD 0
2506.IP "\s-1EV_MAXPRI\s0" 4
2507.IX Item "EV_MAXPRI"
2508.PD
2509The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to
2510\&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can
2511provide for more priorities by overriding those symbols (usually defined
2512to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively).
2513.Sp
2514When doing priority-based operations, libev usually has to linearly search
2515all the priorities, so having many of them (hundreds) uses a lot of space
2516and time, so using the defaults of five priorities (\-2 .. +2) is usually
2517fine.
2518.Sp
2519If your embedding app does not need any priorities, defining these both to
2520\&\f(CW0\fR will save some memory and cpu.
2165.IP "\s-1EV_PERIODIC_ENABLE\s0" 4 2521.IP "\s-1EV_PERIODIC_ENABLE\s0" 4
2166.IX Item "EV_PERIODIC_ENABLE" 2522.IX Item "EV_PERIODIC_ENABLE"
2167If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If 2523If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If
2524defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2525code.
2526.IP "\s-1EV_IDLE_ENABLE\s0" 4
2527.IX Item "EV_IDLE_ENABLE"
2528If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If
2168defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of 2529defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of
2169code. 2530code.
2170.IP "\s-1EV_EMBED_ENABLE\s0" 4 2531.IP "\s-1EV_EMBED_ENABLE\s0" 4
2171.IX Item "EV_EMBED_ENABLE" 2532.IX Item "EV_EMBED_ENABLE"
2172If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If 2533If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If
… …
2187.IP "\s-1EV_PID_HASHSIZE\s0" 4 2548.IP "\s-1EV_PID_HASHSIZE\s0" 4
2188.IX Item "EV_PID_HASHSIZE" 2549.IX Item "EV_PID_HASHSIZE"
2189\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 2550\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2190pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more 2551pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2191than enough. If you need to manage thousands of children you might want to 2552than enough. If you need to manage thousands of children you might want to
2192increase this value. 2553increase this value (\fImust\fR be a power of two).
2554.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2555.IX Item "EV_INOTIFY_HASHSIZE"
2556\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2557inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2558usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2559watchers you might want to increase this value (\fImust\fR be a power of
2560two).
2193.IP "\s-1EV_COMMON\s0" 4 2561.IP "\s-1EV_COMMON\s0" 4
2194.IX Item "EV_COMMON" 2562.IX Item "EV_COMMON"
2195By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2563By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2196this macro to a something else you can include more and other types of 2564this macro to a something else you can include more and other types of
2197members. You have to define it each time you include one of the files, 2565members. You have to define it each time you include one of the files,
… …
2227interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file 2595interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file
2228will be compiled. It is pretty complex because it provides its own header 2596will be compiled. It is pretty complex because it provides its own header
2229file. 2597file.
2230.Sp 2598.Sp
2231The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file 2599The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file
2232that everybody includes and which overrides some autoconf choices: 2600that everybody includes and which overrides some configure choices:
2233.Sp 2601.Sp
2234.Vb 4 2602.Vb 9
2603\& #define EV_MINIMAL 1
2235\& #define EV_USE_POLL 0 2604\& #define EV_USE_POLL 0
2236\& #define EV_MULTIPLICITY 0 2605\& #define EV_MULTIPLICITY 0
2237\& #define EV_PERIODICS 0 2606\& #define EV_PERIODIC_ENABLE 0
2607\& #define EV_STAT_ENABLE 0
2608\& #define EV_FORK_ENABLE 0
2238\& #define EV_CONFIG_H <config.h> 2609\& #define EV_CONFIG_H <config.h>
2610\& #define EV_MINPRI 0
2611\& #define EV_MAXPRI 0
2239.Ve 2612.Ve
2240.Sp 2613.Sp
2241.Vb 1 2614.Vb 1
2242\& #include "ev++.h" 2615\& #include "ev++.h"
2243.Ve 2616.Ve
… …
2251.SH "COMPLEXITIES" 2624.SH "COMPLEXITIES"
2252.IX Header "COMPLEXITIES" 2625.IX Header "COMPLEXITIES"
2253In this section the complexities of (many of) the algorithms used inside 2626In this section the complexities of (many of) the algorithms used inside
2254libev will be explained. For complexity discussions about backends see the 2627libev will be explained. For complexity discussions about backends see the
2255documentation for \f(CW\*(C`ev_default_init\*(C'\fR. 2628documentation for \f(CW\*(C`ev_default_init\*(C'\fR.
2629.Sp
2630All of the following are about amortised time: If an array needs to be
2631extended, libev needs to realloc and move the whole array, but this
2632happens asymptotically never with higher number of elements, so O(1) might
2633mean it might do a lengthy realloc operation in rare cases, but on average
2634it is much faster and asymptotically approaches constant time.
2256.RS 4 2635.RS 4
2257.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 2636.IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4
2258.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 2637.IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)"
2259.PD 0 2638This means that, when you have a watcher that triggers in one hour and
2639there are 100 watchers that would trigger before that then inserting will
2640have to skip those 100 watchers.
2260.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 2641.IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4
2261.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2642.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2643That means that for changing a timer costs less than removing/adding them
2644as only the relative motion in the event queue has to be paid for.
2262.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2645.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2263.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2646.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2264.IP "Stopping check/prepare/idle watchers: O(1)" 4 2647These just add the watcher into an array or at the head of a list.
2265.IX Item "Stopping check/prepare/idle watchers: O(1)" 2648=item Stopping check/prepare/idle watchers: O(1)
2266.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 2649.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2267.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 2650.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2651These watchers are stored in lists then need to be walked to find the
2652correct watcher to remove. The lists are usually short (you don't usually
2653have many watchers waiting for the same fd or signal).
2268.IP "Finding the next timer per loop iteration: O(1)" 4 2654.IP "Finding the next timer per loop iteration: O(1)" 4
2269.IX Item "Finding the next timer per loop iteration: O(1)" 2655.IX Item "Finding the next timer per loop iteration: O(1)"
2656.PD 0
2270.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2657.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2271.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2658.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2659.PD
2660A change means an I/O watcher gets started or stopped, which requires
2661libev to recalculate its status (and possibly tell the kernel).
2272.IP "Activating one watcher: O(1)" 4 2662.IP "Activating one watcher: O(1)" 4
2273.IX Item "Activating one watcher: O(1)" 2663.IX Item "Activating one watcher: O(1)"
2664.PD 0
2665.IP "Priority handling: O(number_of_priorities)" 4
2666.IX Item "Priority handling: O(number_of_priorities)"
2667.PD
2668Priorities are implemented by allocating some space for each
2669priority. When doing priority-based operations, libev usually has to
2670linearly search all the priorities.
2274.RE 2671.RE
2275.RS 4 2672.RS 4
2276.PD
2277.SH "AUTHOR" 2673.SH "AUTHOR"
2278.IX Header "AUTHOR" 2674.IX Header "AUTHOR"
2279Marc Lehmann <libev@schmorp.de>. 2675Marc Lehmann <libev@schmorp.de>.

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